Sequence Back Weld

[nabeel3]

Dear All

Our Company is planning to start welding for 12 mm shell in a carbon steel A 36 Tank. For getting complete penetration we have to do back gouging and weld. After how many pass in the front side shall we back gouge and do back weld. This question arises due to consideration for welding distortion. I have read some where that proper weld sequence will reduce distortion in the weld metal. Or is it enough to finish weld in face side and then go back and do back weld.

Regards

 

[Dhurjati Sen]

Your fabricator would know best, and then the welders.
However, the fit-up is more important than the welding sequence.
Still, after the root from any side, simultaneous welding from inside and outside would minimize distortion to a great extent.

 

[nabeel3]

Hello Mr Sen

The requirement is to grind the root pass , Do DPT and then back weld. Is it OK to grind and weld from back side when welding is ongoing in front side. I mean when the root pass is lost

 

[Dhurjati Sen]

You can grind the root pass and do back gouging too. Also LPI of the root.
Then simultaneous welding from both sides would do no harm.
But, what is the tank service?
Is it not going for too great a quality, or the client / regulations demand it?